Windows Files and Dirs Access Rights Modification Via Icacls

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic identifies the modification of security permissions on files or directories using tools like icacls.exe, cacls.exe, or xcacls.exe. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on specific command-line executions. This activity is significant as it is commonly used by Advanced Persistent Threats (APTs) and coinminer scripts to evade detection and maintain control over compromised systems. If confirmed malicious, this behavior could allow attackers to hinder investigation, impede remediation efforts, and maintain persistent access to the compromised environment.

name: Windows Files and Dirs Access Rights Modification Via Icacls
id: c76b796c-27e1-4520-91c4-4a58695c749e
version: 15
creation_date: '2021-05-07'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: |
    The following analytic identifies the modification of security permissions
    on files or directories using tools like icacls.exe, cacls.exe, or xcacls.exe. It
    leverages data from Endpoint Detection and Response (EDR) agents, focusing on specific
    command-line executions. This activity is significant as it is commonly used by
    Advanced Persistent Threats (APTs) and coinminer scripts to evade detection and
    maintain control over compromised systems. If confirmed malicious, this behavior
    could allow attackers to hinder investigation, impede remediation efforts, and maintain
    persistent access to the compromised environment.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |
    | tstats `security_content_summariesonly` min(_time) as firstTime max(_time)
    as lastTime from datamodel=Endpoint.Processes where
    Processes.process_name IN ("icacls.exe", "cacls.exe","xcacls.exe") AND
    Processes.process IN ("*:R*", "*:W*", "*:F*", "*:C*", "*:N*", "*/P*", "*/E*")
    by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
    Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
    Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
    Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
    Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_files_and_dirs_access_rights_modification_via_icacls_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: No false positives have been identified at this time. Filter as needed.
references:
    - https://malpedia.caad.fkie.fraunhofer.de/details/win.amadey
drilldown_searches:
    - name: View the detection results for - "$dest$" and "$user$"
      search: '%original_detection_search% | search  dest = "$dest$" user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$" and "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 30
          message: Process name $process_name$ with access right modification argument executed by $user$ to change security permission of a specific file or directory on host $dest$
        - field: user
          type: user
          score: 30
          message: Process name $process_name$ with access right modification argument executed by $user$ to change security permission of a specific file or directory on host $dest$
analytic_story:
    - Amadey
    - Defense Evasion or Unauthorized Access Via SDDL Tampering
asset_type: Endpoint
atomic_guid:
    - 3309f53e-b22b-4eb6-8fd2-a6cf58b355a9
mitre_attack_id:
    - T1222.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/amadey/access_permission/amadey_sysmon2.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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Executable code, not a declarative rule

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Format & documentation suggestions

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